Details | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
6417 | ashmew2 | 1 | /* |
2 | * jccolor.c |
||
3 | * |
||
4 | * Copyright (C) 1991-1996, Thomas G. Lane. |
||
5 | * This file is part of the Independent JPEG Group's software. |
||
6 | * For conditions of distribution and use, see the accompanying README file. |
||
7 | * |
||
8 | * This file contains input colorspace conversion routines. |
||
9 | */ |
||
10 | |||
11 | #define JPEG_INTERNALS |
||
12 | #include "jinclude.h" |
||
13 | #include "jpeglib.h" |
||
14 | |||
15 | |||
16 | /* Private subobject */ |
||
17 | |||
18 | typedef struct { |
||
19 | struct jpeg_color_converter pub; /* public fields */ |
||
20 | |||
21 | /* Private state for RGB->YCC conversion */ |
||
22 | INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */ |
||
23 | } my_color_converter; |
||
24 | |||
25 | typedef my_color_converter * my_cconvert_ptr; |
||
26 | |||
27 | |||
28 | /**************** RGB -> YCbCr conversion: most common case **************/ |
||
29 | |||
30 | /* |
||
31 | * YCbCr is defined per CCIR 601-1, except that Cb and Cr are |
||
32 | * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5. |
||
33 | * The conversion equations to be implemented are therefore |
||
34 | * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B |
||
35 | * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE |
||
36 | * Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE |
||
37 | * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.) |
||
38 | * Note: older versions of the IJG code used a zero offset of MAXJSAMPLE/2, |
||
39 | * rather than CENTERJSAMPLE, for Cb and Cr. This gave equal positive and |
||
40 | * negative swings for Cb/Cr, but meant that grayscale values (Cb=Cr=0) |
||
41 | * were not represented exactly. Now we sacrifice exact representation of |
||
42 | * maximum red and maximum blue in order to get exact grayscales. |
||
43 | * |
||
44 | * To avoid floating-point arithmetic, we represent the fractional constants |
||
45 | * as integers scaled up by 2^16 (about 4 digits precision); we have to divide |
||
46 | * the products by 2^16, with appropriate rounding, to get the correct answer. |
||
47 | * |
||
48 | * For even more speed, we avoid doing any multiplications in the inner loop |
||
49 | * by precalculating the constants times R,G,B for all possible values. |
||
50 | * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table); |
||
51 | * for 12-bit samples it is still acceptable. It's not very reasonable for |
||
52 | * 16-bit samples, but if you want lossless storage you shouldn't be changing |
||
53 | * colorspace anyway. |
||
54 | * The CENTERJSAMPLE offsets and the rounding fudge-factor of 0.5 are included |
||
55 | * in the tables to save adding them separately in the inner loop. |
||
56 | */ |
||
57 | |||
58 | #define SCALEBITS 16 /* speediest right-shift on some machines */ |
||
59 | #define CBCR_OFFSET ((INT32) CENTERJSAMPLE << SCALEBITS) |
||
60 | #define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) |
||
61 | #define FIX(x) ((INT32) ((x) * (1L< |
||
62 | |||
63 | /* We allocate one big table and divide it up into eight parts, instead of |
||
64 | * doing eight alloc_small requests. This lets us use a single table base |
||
65 | * address, which can be held in a register in the inner loops on many |
||
66 | * machines (more than can hold all eight addresses, anyway). |
||
67 | */ |
||
68 | |||
69 | #define R_Y_OFF 0 /* offset to R => Y section */ |
||
70 | #define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */ |
||
71 | #define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */ |
||
72 | #define R_CB_OFF (3*(MAXJSAMPLE+1)) |
||
73 | #define G_CB_OFF (4*(MAXJSAMPLE+1)) |
||
74 | #define B_CB_OFF (5*(MAXJSAMPLE+1)) |
||
75 | #define R_CR_OFF B_CB_OFF /* B=>Cb, R=>Cr are the same */ |
||
76 | #define G_CR_OFF (6*(MAXJSAMPLE+1)) |
||
77 | #define B_CR_OFF (7*(MAXJSAMPLE+1)) |
||
78 | #define TABLE_SIZE (8*(MAXJSAMPLE+1)) |
||
79 | |||
80 | |||
81 | /* |
||
82 | * Initialize for RGB->YCC colorspace conversion. |
||
83 | */ |
||
84 | |||
85 | METHODDEF(void) |
||
86 | rgb_ycc_start (j_compress_ptr cinfo) |
||
87 | { |
||
88 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; |
||
89 | INT32 * rgb_ycc_tab; |
||
90 | INT32 i; |
||
91 | |||
92 | /* Allocate and fill in the conversion tables. */ |
||
93 | cconvert->rgb_ycc_tab = rgb_ycc_tab = (INT32 *) |
||
94 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
||
95 | (TABLE_SIZE * SIZEOF(INT32))); |
||
96 | |||
97 | for (i = 0; i <= MAXJSAMPLE; i++) { |
||
98 | rgb_ycc_tab[i+R_Y_OFF] = FIX(0.29900) * i; |
||
99 | rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i; |
||
100 | rgb_ycc_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF; |
||
101 | rgb_ycc_tab[i+R_CB_OFF] = (-FIX(0.16874)) * i; |
||
102 | rgb_ycc_tab[i+G_CB_OFF] = (-FIX(0.33126)) * i; |
||
103 | /* We use a rounding fudge-factor of 0.5-epsilon for Cb and Cr. |
||
104 | * This ensures that the maximum output will round to MAXJSAMPLE |
||
105 | * not MAXJSAMPLE+1, and thus that we don't have to range-limit. |
||
106 | */ |
||
107 | rgb_ycc_tab[i+B_CB_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1; |
||
108 | /* B=>Cb and R=>Cr tables are the same |
||
109 | rgb_ycc_tab[i+R_CR_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1; |
||
110 | */ |
||
111 | rgb_ycc_tab[i+G_CR_OFF] = (-FIX(0.41869)) * i; |
||
112 | rgb_ycc_tab[i+B_CR_OFF] = (-FIX(0.08131)) * i; |
||
113 | } |
||
114 | } |
||
115 | |||
116 | |||
117 | /* |
||
118 | * Convert some rows of samples to the JPEG colorspace. |
||
119 | * |
||
120 | * Note that we change from the application's interleaved-pixel format |
||
121 | * to our internal noninterleaved, one-plane-per-component format. |
||
122 | * The input buffer is therefore three times as wide as the output buffer. |
||
123 | * |
||
124 | * A starting row offset is provided only for the output buffer. The caller |
||
125 | * can easily adjust the passed input_buf value to accommodate any row |
||
126 | * offset required on that side. |
||
127 | */ |
||
128 | |||
129 | METHODDEF(void) |
||
130 | rgb_ycc_convert (j_compress_ptr cinfo, |
||
131 | JSAMPARRAY input_buf, JSAMPIMAGE output_buf, |
||
132 | JDIMENSION output_row, int num_rows) |
||
133 | { |
||
134 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; |
||
135 | register int r, g, b; |
||
136 | register INT32 * ctab = cconvert->rgb_ycc_tab; |
||
137 | register JSAMPROW inptr; |
||
138 | register JSAMPROW outptr0, outptr1, outptr2; |
||
139 | register JDIMENSION col; |
||
140 | JDIMENSION num_cols = cinfo->image_width; |
||
141 | |||
142 | while (--num_rows >= 0) { |
||
143 | inptr = *input_buf++; |
||
144 | outptr0 = output_buf[0][output_row]; |
||
145 | outptr1 = output_buf[1][output_row]; |
||
146 | outptr2 = output_buf[2][output_row]; |
||
147 | output_row++; |
||
148 | for (col = 0; col < num_cols; col++) { |
||
149 | r = GETJSAMPLE(inptr[RGB_RED]); |
||
150 | g = GETJSAMPLE(inptr[RGB_GREEN]); |
||
151 | b = GETJSAMPLE(inptr[RGB_BLUE]); |
||
152 | inptr += RGB_PIXELSIZE; |
||
153 | /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations |
||
154 | * must be too; we do not need an explicit range-limiting operation. |
||
155 | * Hence the value being shifted is never negative, and we don't |
||
156 | * need the general RIGHT_SHIFT macro. |
||
157 | */ |
||
158 | /* Y */ |
||
159 | outptr0[col] = (JSAMPLE) |
||
160 | ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF]) |
||
161 | >> SCALEBITS); |
||
162 | /* Cb */ |
||
163 | outptr1[col] = (JSAMPLE) |
||
164 | ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF]) |
||
165 | >> SCALEBITS); |
||
166 | /* Cr */ |
||
167 | outptr2[col] = (JSAMPLE) |
||
168 | ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF]) |
||
169 | >> SCALEBITS); |
||
170 | } |
||
171 | } |
||
172 | } |
||
173 | |||
174 | |||
175 | /**************** Cases other than RGB -> YCbCr **************/ |
||
176 | |||
177 | |||
178 | /* |
||
179 | * Convert some rows of samples to the JPEG colorspace. |
||
180 | * This version handles RGB->grayscale conversion, which is the same |
||
181 | * as the RGB->Y portion of RGB->YCbCr. |
||
182 | * We assume rgb_ycc_start has been called (we only use the Y tables). |
||
183 | */ |
||
184 | |||
185 | METHODDEF(void) |
||
186 | rgb_gray_convert (j_compress_ptr cinfo, |
||
187 | JSAMPARRAY input_buf, JSAMPIMAGE output_buf, |
||
188 | JDIMENSION output_row, int num_rows) |
||
189 | { |
||
190 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; |
||
191 | register int r, g, b; |
||
192 | register INT32 * ctab = cconvert->rgb_ycc_tab; |
||
193 | register JSAMPROW inptr; |
||
194 | register JSAMPROW outptr; |
||
195 | register JDIMENSION col; |
||
196 | JDIMENSION num_cols = cinfo->image_width; |
||
197 | |||
198 | while (--num_rows >= 0) { |
||
199 | inptr = *input_buf++; |
||
200 | outptr = output_buf[0][output_row]; |
||
201 | output_row++; |
||
202 | for (col = 0; col < num_cols; col++) { |
||
203 | r = GETJSAMPLE(inptr[RGB_RED]); |
||
204 | g = GETJSAMPLE(inptr[RGB_GREEN]); |
||
205 | b = GETJSAMPLE(inptr[RGB_BLUE]); |
||
206 | inptr += RGB_PIXELSIZE; |
||
207 | /* Y */ |
||
208 | outptr[col] = (JSAMPLE) |
||
209 | ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF]) |
||
210 | >> SCALEBITS); |
||
211 | } |
||
212 | } |
||
213 | } |
||
214 | |||
215 | |||
216 | /* |
||
217 | * Convert some rows of samples to the JPEG colorspace. |
||
218 | * This version handles Adobe-style CMYK->YCCK conversion, |
||
219 | * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the same |
||
220 | * conversion as above, while passing K (black) unchanged. |
||
221 | * We assume rgb_ycc_start has been called. |
||
222 | */ |
||
223 | |||
224 | METHODDEF(void) |
||
225 | cmyk_ycck_convert (j_compress_ptr cinfo, |
||
226 | JSAMPARRAY input_buf, JSAMPIMAGE output_buf, |
||
227 | JDIMENSION output_row, int num_rows) |
||
228 | { |
||
229 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; |
||
230 | register int r, g, b; |
||
231 | register INT32 * ctab = cconvert->rgb_ycc_tab; |
||
232 | register JSAMPROW inptr; |
||
233 | register JSAMPROW outptr0, outptr1, outptr2, outptr3; |
||
234 | register JDIMENSION col; |
||
235 | JDIMENSION num_cols = cinfo->image_width; |
||
236 | |||
237 | while (--num_rows >= 0) { |
||
238 | inptr = *input_buf++; |
||
239 | outptr0 = output_buf[0][output_row]; |
||
240 | outptr1 = output_buf[1][output_row]; |
||
241 | outptr2 = output_buf[2][output_row]; |
||
242 | outptr3 = output_buf[3][output_row]; |
||
243 | output_row++; |
||
244 | for (col = 0; col < num_cols; col++) { |
||
245 | r = MAXJSAMPLE - GETJSAMPLE(inptr[0]); |
||
246 | g = MAXJSAMPLE - GETJSAMPLE(inptr[1]); |
||
247 | b = MAXJSAMPLE - GETJSAMPLE(inptr[2]); |
||
248 | /* K passes through as-is */ |
||
249 | outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */ |
||
250 | inptr += 4; |
||
251 | /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations |
||
252 | * must be too; we do not need an explicit range-limiting operation. |
||
253 | * Hence the value being shifted is never negative, and we don't |
||
254 | * need the general RIGHT_SHIFT macro. |
||
255 | */ |
||
256 | /* Y */ |
||
257 | outptr0[col] = (JSAMPLE) |
||
258 | ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF]) |
||
259 | >> SCALEBITS); |
||
260 | /* Cb */ |
||
261 | outptr1[col] = (JSAMPLE) |
||
262 | ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF]) |
||
263 | >> SCALEBITS); |
||
264 | /* Cr */ |
||
265 | outptr2[col] = (JSAMPLE) |
||
266 | ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF]) |
||
267 | >> SCALEBITS); |
||
268 | } |
||
269 | } |
||
270 | } |
||
271 | |||
272 | |||
273 | /* |
||
274 | * Convert some rows of samples to the JPEG colorspace. |
||
275 | * This version handles grayscale output with no conversion. |
||
276 | * The source can be either plain grayscale or YCbCr (since Y == gray). |
||
277 | */ |
||
278 | |||
279 | METHODDEF(void) |
||
280 | grayscale_convert (j_compress_ptr cinfo, |
||
281 | JSAMPARRAY input_buf, JSAMPIMAGE output_buf, |
||
282 | JDIMENSION output_row, int num_rows) |
||
283 | { |
||
284 | register JSAMPROW inptr; |
||
285 | register JSAMPROW outptr; |
||
286 | register JDIMENSION col; |
||
287 | JDIMENSION num_cols = cinfo->image_width; |
||
288 | int instride = cinfo->input_components; |
||
289 | |||
290 | while (--num_rows >= 0) { |
||
291 | inptr = *input_buf++; |
||
292 | outptr = output_buf[0][output_row]; |
||
293 | output_row++; |
||
294 | for (col = 0; col < num_cols; col++) { |
||
295 | outptr[col] = inptr[0]; /* don't need GETJSAMPLE() here */ |
||
296 | inptr += instride; |
||
297 | } |
||
298 | } |
||
299 | } |
||
300 | |||
301 | |||
302 | /* |
||
303 | * Convert some rows of samples to the JPEG colorspace. |
||
304 | * This version handles multi-component colorspaces without conversion. |
||
305 | * We assume input_components == num_components. |
||
306 | */ |
||
307 | |||
308 | METHODDEF(void) |
||
309 | null_convert (j_compress_ptr cinfo, |
||
310 | JSAMPARRAY input_buf, JSAMPIMAGE output_buf, |
||
311 | JDIMENSION output_row, int num_rows) |
||
312 | { |
||
313 | register JSAMPROW inptr; |
||
314 | register JSAMPROW outptr; |
||
315 | register JDIMENSION col; |
||
316 | register int ci; |
||
317 | int nc = cinfo->num_components; |
||
318 | JDIMENSION num_cols = cinfo->image_width; |
||
319 | |||
320 | while (--num_rows >= 0) { |
||
321 | /* It seems fastest to make a separate pass for each component. */ |
||
322 | for (ci = 0; ci < nc; ci++) { |
||
323 | inptr = *input_buf; |
||
324 | outptr = output_buf[ci][output_row]; |
||
325 | for (col = 0; col < num_cols; col++) { |
||
326 | outptr[col] = inptr[ci]; /* don't need GETJSAMPLE() here */ |
||
327 | inptr += nc; |
||
328 | } |
||
329 | } |
||
330 | input_buf++; |
||
331 | output_row++; |
||
332 | } |
||
333 | } |
||
334 | |||
335 | |||
336 | /* |
||
337 | * Empty method for start_pass. |
||
338 | */ |
||
339 | |||
340 | METHODDEF(void) |
||
341 | null_method (j_compress_ptr cinfo) |
||
342 | { |
||
343 | /* no work needed */ |
||
344 | } |
||
345 | |||
346 | |||
347 | /* |
||
348 | * Module initialization routine for input colorspace conversion. |
||
349 | */ |
||
350 | |||
351 | GLOBAL(void) |
||
352 | jinit_color_converter (j_compress_ptr cinfo) |
||
353 | { |
||
354 | my_cconvert_ptr cconvert; |
||
355 | |||
356 | cconvert = (my_cconvert_ptr) |
||
357 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
||
358 | SIZEOF(my_color_converter)); |
||
359 | cinfo->cconvert = (struct jpeg_color_converter *) cconvert; |
||
360 | /* set start_pass to null method until we find out differently */ |
||
361 | cconvert->pub.start_pass = null_method; |
||
362 | |||
363 | /* Make sure input_components agrees with in_color_space */ |
||
364 | switch (cinfo->in_color_space) { |
||
365 | case JCS_GRAYSCALE: |
||
366 | if (cinfo->input_components != 1) |
||
367 | ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); |
||
368 | break; |
||
369 | |||
370 | case JCS_RGB: |
||
371 | #if RGB_PIXELSIZE != 3 |
||
372 | if (cinfo->input_components != RGB_PIXELSIZE) |
||
373 | ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); |
||
374 | break; |
||
375 | #endif /* else share code with YCbCr */ |
||
376 | |||
377 | case JCS_YCbCr: |
||
378 | if (cinfo->input_components != 3) |
||
379 | ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); |
||
380 | break; |
||
381 | |||
382 | case JCS_CMYK: |
||
383 | case JCS_YCCK: |
||
384 | if (cinfo->input_components != 4) |
||
385 | ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); |
||
386 | break; |
||
387 | |||
388 | default: /* JCS_UNKNOWN can be anything */ |
||
389 | if (cinfo->input_components < 1) |
||
390 | ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); |
||
391 | break; |
||
392 | } |
||
393 | |||
394 | /* Check num_components, set conversion method based on requested space */ |
||
395 | switch (cinfo->jpeg_color_space) { |
||
396 | case JCS_GRAYSCALE: |
||
397 | if (cinfo->num_components != 1) |
||
398 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); |
||
399 | if (cinfo->in_color_space == JCS_GRAYSCALE) |
||
400 | cconvert->pub.color_convert = grayscale_convert; |
||
401 | else if (cinfo->in_color_space == JCS_RGB) { |
||
402 | cconvert->pub.start_pass = rgb_ycc_start; |
||
403 | cconvert->pub.color_convert = rgb_gray_convert; |
||
404 | } else if (cinfo->in_color_space == JCS_YCbCr) |
||
405 | cconvert->pub.color_convert = grayscale_convert; |
||
406 | else |
||
407 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); |
||
408 | break; |
||
409 | |||
410 | case JCS_RGB: |
||
411 | if (cinfo->num_components != 3) |
||
412 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); |
||
413 | if (cinfo->in_color_space == JCS_RGB && RGB_PIXELSIZE == 3) |
||
414 | cconvert->pub.color_convert = null_convert; |
||
415 | else |
||
416 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); |
||
417 | break; |
||
418 | |||
419 | case JCS_YCbCr: |
||
420 | if (cinfo->num_components != 3) |
||
421 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); |
||
422 | if (cinfo->in_color_space == JCS_RGB) { |
||
423 | cconvert->pub.start_pass = rgb_ycc_start; |
||
424 | cconvert->pub.color_convert = rgb_ycc_convert; |
||
425 | } else if (cinfo->in_color_space == JCS_YCbCr) |
||
426 | cconvert->pub.color_convert = null_convert; |
||
427 | else |
||
428 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); |
||
429 | break; |
||
430 | |||
431 | case JCS_CMYK: |
||
432 | if (cinfo->num_components != 4) |
||
433 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); |
||
434 | if (cinfo->in_color_space == JCS_CMYK) |
||
435 | cconvert->pub.color_convert = null_convert; |
||
436 | else |
||
437 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); |
||
438 | break; |
||
439 | |||
440 | case JCS_YCCK: |
||
441 | if (cinfo->num_components != 4) |
||
442 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); |
||
443 | if (cinfo->in_color_space == JCS_CMYK) { |
||
444 | cconvert->pub.start_pass = rgb_ycc_start; |
||
445 | cconvert->pub.color_convert = cmyk_ycck_convert; |
||
446 | } else if (cinfo->in_color_space == JCS_YCCK) |
||
447 | cconvert->pub.color_convert = null_convert; |
||
448 | else |
||
449 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); |
||
450 | break; |
||
451 | |||
452 | default: /* allow null conversion of JCS_UNKNOWN */ |
||
453 | if (cinfo->jpeg_color_space != cinfo->in_color_space || |
||
454 | cinfo->num_components != cinfo->input_components) |
||
455 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); |
||
456 | cconvert->pub.color_convert = null_convert; |
||
457 | break; |
||
458 | } |
||
459 | }>>>>>>>=> |